"And what does Bill get in this deal?"
The continued use of his senses and limbs.
At minimum Bill gets to strategize another presidential campaign, which he loves to do. If she wins, he's back living in the White House, with a supply of fresh interns close by. Plus, I believe he wants her Senate seat and has a plan to step into it.
Let's him continue to get visits from his highly paid "discreet" call girls.